Method for shouldering monocrystalline silicon

Abstract

The invention discloses a single crystal silicon shouldering method. The single crystal silicon shouldering method comprises the following steps: controlling the power of a single crystal furnace to be reduced to a first preset power value within a first preset time; acquiring the diameter of the monocrystalline silicon in real time, and judging whether the diameter of the monocrystalline silicon reaches a first preset diameter or not within a first preset time; if the diameter of the single crystal silicon does not reach the first preset diameter, controlling the power of the single crystal furnace to be reduced to a second preset power value within a second preset time; if the diameter of the monocrystalline silicon reaches the first preset diameter, obtaining a first actual time when the monocrystalline silicon reaches the first preset diameter; and determining that the first actual time is less than or equal to the first preset time, and controlling the power of the single crystal furnace to be reduced to a second preset power value from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter within a third preset time from when the single crystal silicon reaches the first preset diameter. According to the shouldering method of the monocrystalline silicon, the survival rate and the quality of the monocrystalline silicon are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal growth, and more particularly to a shoulder placement method for single crystal silicon. Background Art

[0002] In the process of growing single crystal silicon, the shoulder release process is an essential step. However, the existing single crystal furnaces usually simply reduce the power according to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, or fix the pulling speed according to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. However, in the actual crystal pulling process, due to factors such as inconsistent temperature changes in each single crystal furnace, sudden temperature changes or changes in the external environment, it is easy to cause the actual diameter of the single crystal silicon to differ too much from the target diameter, resulting in shoulder release failure. Once the shoulder release fails, the shoulder needs to be removed or melted back, resulting in a huge waste of time and cost. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a shouldering method for single crystal silicon, wherein the shouldering method for single crystal silicon adjusts the power reduction amplitude of a single crystal furnace according to the shouldering temperature, so that the actual diameter of the single crystal silicon grows as close to the preset diameter as possible, thereby improving the survival rate and quality of the single crystal silicon.

[0004] According to the shoulder release method of single crystal silicon in accordance with the embodiment of the invention, the method includes: controlling the power of the single crystal furnace to be reduced to a first preset power value within a first preset time; obtaining the diameter of the single crystal silicon in real time, and judging whether the diameter of the single crystal silicon reaches the first preset diameter within the first preset time; if the diameter of the single crystal silicon does not reach the first preset diameter, controlling the power of the single crystal furnace to be reduced to a second preset power value within a second preset time; if the diameter of the single crystal silicon reaches the first preset diameter, obtaining the first actual time when the single crystal silicon reaches the first preset diameter; determining that the first actual time is less than or equal to the first preset time, and controlling the power of the single crystal furnace to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time from the time when the single crystal silicon reaches the first preset diameter, wherein the third preset time is greater than the second preset time.

[0005] According to the shoulder releasing method of single crystal silicon according to an embodiment of the present invention, the power of the single crystal furnace is controlled to be reduced to a first preset power value within a first preset time, the diameter of the single crystal silicon is obtained in real time, and it is determined whether the diameter of the single crystal silicon reaches the first preset diameter within the first preset time, thereby determining the height of the shoulder releasing temperature based on the diameter of the single crystal silicon obtained in real time. If the diameter of the single crystal silicon does not reach the first preset diameter, the power of the single crystal furnace is controlled to be reduced to the second preset power value within the second preset time; if the diameter of the single crystal silicon reaches the first preset diameter, the first actual time when the single crystal silicon reaches the first preset diameter is obtained, and by determining that the first actual time is less than or equal to the first preset time, the power of the single crystal furnace is controlled to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time from the time when the single crystal silicon reaches the first preset diameter, wherein the third preset time is greater than the second preset time, so as to adjust the power reduction amplitude of the single crystal furnace according to the height of this shoulder release temperature, so that the actual diameter of the single crystal silicon grows according to the preset diameter as much as possible, thereby increasing the stability of the single crystal silicon shoulder release process, improving the survival rate and quality of single crystal silicon, and being suitable for the growth of large-size single crystal silicon.

[0006] In some embodiments of the present invention, within the first preset time, if the diameter of the single crystal silicon does not reach the first preset diameter, and the diameter of the single crystal silicon after the first preset time is the first actual diameter, the calculation formula for the second preset time is: second preset time = fourth preset time - (first preset diameter - first actual diameter) * 2.

[0007] In some embodiments of the present invention, the second preset time is greater than or equal to 10 minutes.

[0008] In some embodiments of the present invention, the calculation formula of the third preset time is: third preset time=(first preset time-first actual time)*2+fourth preset time.

[0009] In some embodiments of the present invention, the third preset time is less than or equal to 140 minutes.

[0010] In some embodiments of the present invention, after controlling the power of the single crystal furnace to be reduced to a second preset power value within a second preset time, the shoulder release method further includes: when the power of the single crystal furnace is reduced to the second preset power value, determining that the diameter of the single crystal silicon has not reached the second preset diameter; controlling the single crystal furnace to keep running at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter, and the second preset diameter is larger than the first preset diameter.

[0011] In some embodiments of the present invention, the power of the single crystal furnace is controlled to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time starting from the time when the single crystal silicon reaches the first preset diameter, wherein after the third preset time is greater than the second preset time, the shoulder release method further includes: determining that the diameter of the single crystal silicon reaches the second preset diameter and the second actual time when the diameter of the single crystal silicon reaches the second preset diameter is less than the third preset time, and the second preset diameter is greater than the first preset diameter; and controlling the pulling speed of the single crystal silicon according to the length of the single crystal silicon until the third preset time is reached.

[0012] In some embodiments of the present invention, the shoulder release method further includes: adjusting the power of the single crystal furnace according to the length of the single crystal silicon.

[0013] In some embodiments of the present invention, the shoulder release method also includes: determining that the diameter of the single crystal silicon reaches a third preset diameter, and the third preset diameter is greater than the second preset diameter; taking the current power value of the single crystal furnace as the starting value, and uniformly reducing the power value of the single crystal furnace to a third preset power value according to the growth rate of the diameter of the single crystal silicon during the process in which the diameter of the single crystal silicon increases from the third preset diameter to a fourth preset diameter, and the fourth preset diameter is greater than the third preset diameter.

[0014] In some embodiments of the present invention, the shoulder release method also includes: obtaining an actual diameter of the single crystal silicon, determining whether the actual diameter reaches the fork diameter or determining whether the shoulder release operation time of the single crystal silicon reaches the fork setting time; if so, controlling the pulling speed of the single crystal silicon according to the actual fork width of the single crystal silicon; if not, and the single crystal silicon is forked, increasing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon.

[0015] In some embodiments of the present invention, controlling the pulling speed of the single crystal silicon according to the actual fork width of the single crystal silicon includes: if the actual fork width is smaller than the target fork width, reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon; if the actual fork width is greater than or equal to the target fork width, controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon.

[0016] In some embodiments of the present invention, reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon includes: controlling the pulling speed of the single crystal furnace to decrease from the target pulling speed value to a first lower limit pulling speed value; controlling the single crystal furnace to increase at the first pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon.

[0017] In some embodiments of the present invention, the pulling speed of the single crystal furnace is maintained at the first lower limit pulling speed value for a time that is less than or equal to the first lower limit time.

[0018] In some embodiments of the present invention, the calculation formula for the first lower limit pulling speed value is: (actual fork width of single crystal silicon - target fork width of single crystal furnace corresponding to the shoulder time of single crystal silicon or the length of single crystal silicon) * stage speed adjustment ratio of single crystal furnace corresponding to the shoulder time of single crystal silicon or the length of single crystal silicon * target pulling speed value of single crystal furnace corresponding to the shoulder time of single crystal silicon or the length of single crystal silicon.

[0019] In some embodiments of the present invention, controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon includes: if the actual diameter change rate is greater than the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is greater than the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon, increasing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon; if the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is greater than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon If the actual pulling speed value is less than the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon, the pulling speed is reduced on the basis of the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon; if the actual diameter change rate is equal to the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, the actual pulling speed value of the single crystal furnace is maintained; if the actual diameter change rate is less than the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, the pulling speed is reduced on the basis of the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon.

[0020] In some embodiments of the present invention, the actual diameter change rate is smaller than the target diameter change rate of the single crystal silicon corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, and reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon includes: controlling the single crystal furnace to reduce the second pulling speed to a second lower limit pulling speed value; determining that the pulling speed of the single crystal furnace is reduced to the second lower limit pulling speed value; controlling the single crystal furnace to increase the third pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, and the second pulling speed is smaller than the third pulling speed.

[0021] In some embodiments of the present invention, the pulling speed of the single crystal furnace is maintained at the second lower limit pulling speed value for a time that is less than or equal to the second lower limit time.

[0022] In some embodiments of the present invention, if the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon includes: controlling the pulling speed of the single crystal furnace to decrease from the target pulling speed value to a third lower limit pulling speed value; controlling the single crystal furnace to increase at a fourth pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon.

[0023] In some embodiments of the present invention, the calculation formula for the second lower limit pulling speed value or the third lower limit pulling speed value is: (actual diameter change rate of the single crystal silicon - target diameter change rate of the single crystal silicon corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon) * stage speed adjustment ratio of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon * target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0026] Figure 1 is a flow chart of a method for shouldering single crystal silicon according to an embodiment of the present invention;

[0027] Figure 2FIG. 4 is a flow chart of a method for shouldering single crystal silicon according to yet another embodiment of the present invention. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] The following describes a method for removing shoulders of single crystal silicon according to an embodiment of the present invention with reference to the accompanying drawings.

[0032] like Figure 1 As shown, the shoulder release method of single crystal silicon according to an embodiment of the present invention includes:

[0033] The power of the single crystal furnace is controlled to be reduced to a first preset power value within a first preset time. It is understandable that, in the process of single crystal silicon growth, the lower the temperature in the single crystal furnace, the faster the diameter of the single crystal furnace grows. Therefore, when the single crystal silicon reaches the shoulder release process, the power of the single crystal furnace is reduced to reduce the temperature in the single crystal furnace so that the length of the single crystal silicon diameter becomes longer, and the power of the single crystal furnace is controlled to be reduced to a first preset power value within a first preset time, so as to judge the shoulder release temperature according to the actual diameter of the single crystal silicon, and then perform the subsequent steps of the shoulder release method of the single crystal silicon.

[0034] The diameter of the single crystal silicon is obtained in real time, and it is determined whether the diameter of the single crystal silicon reaches the first preset diameter within the first preset time. It can be understood that during the ideal state of the shoulder release process of the preset single crystal silicon, when the power of the single crystal furnace is reduced to the first preset power value within the first preset time, the diameter of the single crystal silicon obtained in real time is the first preset diameter. Therefore, by judging whether the real-time diameter of the single crystal silicon obtained within the first preset time reaches the first preset diameter through this step, the height of the shoulder release temperature is judged, and then the subsequent steps of the shoulder release method of the single crystal silicon are executed, so as to effectively avoid the problem of mismatch between the power reduction of the single crystal furnace and the actual diameter during the shoulder release process, and improve the success rate of shoulder release of the single crystal.

[0035] If the diameter of the single crystal silicon does not reach the first preset diameter, the power of the single crystal furnace is controlled to be reduced to the second preset power value within the second preset time. It can be understood that when the real-time diameter of the single crystal silicon obtained in the above step within the first preset time does not reach the first preset diameter, it means that the shoulder is a high-temperature shoulder. Therefore, in the subsequent shoulder release process, it is necessary to shorten the power reduction time of the single crystal furnace. Thus, by controlling the power of the single crystal furnace to be reduced to the second preset power value within the second preset time, the growth rate of the single crystal silicon diameter is faster, so that the actual diameter of the single crystal silicon grows as much as possible according to the preset diameter, thereby ensuring the survival rate and quality of the single crystal silicon. It should be noted that the calculation method of the second preset time is specifically described in the subsequent embodiments.

[0036] If the diameter of the single crystal silicon reaches the first preset diameter, the first actual time when the single crystal silicon reaches the first preset diameter is obtained. Thus, through the above steps, the diameter of the single crystal silicon reaches the first preset diameter in real time, and the first actual time when the single crystal silicon reaches the first preset diameter is obtained, so as to judge the height of the shoulder release temperature according to the first actual time, and then perform the subsequent steps of the shoulder release method of the single crystal silicon.

[0037] Determine that the first actual time is less than or equal to the first preset time, and control the power of the single crystal furnace to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within the third preset time from when the single crystal silicon reaches the first preset diameter, wherein the third preset time is greater than the second preset time. Thus, when the first actual time when the single crystal silicon reaches the first preset diameter in the above step is equal to the first preset time, it indicates that the shoulder release is in an ideal state; or, when the first actual time when the single crystal silicon reaches the first preset diameter in the above step is less than the first preset time, it indicates that the shoulder release is a low-temperature shoulder. Therefore, in the subsequent shoulder release process, it is necessary to reduce the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within the third preset time from the first actual time when the single crystal silicon reaches the first preset diameter, so that the actual diameter of the single crystal silicon grows as much as possible according to the preset diameter, thereby ensuring the survival rate and quality of the single crystal silicon. It should be noted that the calculation method of the third preset time is specifically described in the subsequent embodiments.

[0038] According to the shoulder releasing method of single crystal silicon according to an embodiment of the present invention, the power of the single crystal furnace is controlled to be reduced to a first preset power value within a first preset time, the diameter of the single crystal silicon is obtained in real time, and it is determined whether the diameter of the single crystal silicon reaches the first preset diameter within the first preset time, thereby determining the height of the shoulder releasing temperature based on the diameter of the single crystal silicon obtained in real time. If the diameter of the single crystal silicon does not reach the first preset diameter, the power of the single crystal furnace is controlled to be reduced to the second preset power value within the second preset time; if the diameter of the single crystal silicon reaches the first preset diameter, the first actual time when the single crystal silicon reaches the first preset diameter is obtained, and by determining that the first actual time is less than or equal to the first preset time, the power of the single crystal furnace is controlled to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time from the time when the single crystal silicon reaches the first preset diameter, wherein the third preset time is greater than the second preset time, so as to adjust the power reduction amplitude of the single crystal furnace according to the height of this shoulder release temperature, so that the actual diameter of the single crystal silicon grows according to the preset diameter as much as possible, thereby increasing the stability of the single crystal silicon shoulder release process, improving the survival rate and quality of single crystal silicon, and being suitable for the growth of large-size single crystal silicon.

[0039] In some embodiments of the present invention, within the first preset time, if the diameter of the single crystal silicon does not reach the first preset diameter, and the diameter of the single crystal silicon after the first preset time is the first actual diameter, the calculation formula for the second preset time is: second preset time = (fourth preset time - (first preset diameter - first actual diameter)) * 2.

[0040] It can be understood that in the process of preset shoulder release process of single crystal silicon in an ideal state, the first stage of shoulder release process of single crystal silicon: the power of the single crystal furnace is reduced to the first preset power value within the first preset time, and the diameter of the single crystal silicon reaches the first preset diameter; the second stage of shoulder release process of single crystal silicon: the power of the single crystal furnace is reduced to the second preset power value within the fourth preset time, and the diameter of the single crystal silicon reaches the second preset diameter. Therefore, the second preset time is obtained by the fourth preset time, the first preset diameter and the first actual diameter of the single crystal silicon after the first preset time, and according to the formula: fourth preset time-(first preset diameter-first actual diameter))*2, and the power of the single crystal furnace is controlled to be reduced to the second preset power value within the second preset time.

[0041] For example, in a specific embodiment of the present invention, during the shoulder releasing process of the preset single crystal silicon in an ideal state, the initial power of the single crystal furnace is 1800APC (where 1KW=30APC), and the first stage of the shoulder releasing process of the single crystal silicon: the power of the single crystal furnace is reduced to 1750APC (first preset power value) within 60min (first preset time), and the diameter of the single crystal silicon reaches 50mm (first preset diameter); the second stage of the shoulder releasing process of the single crystal silicon: the power of the single crystal furnace is reduced to 1700APC (second preset power value) within 40min (fourth preset time), and the diameter of the single crystal silicon reaches 100mm (second preset diameter).

[0042] When the power of the single crystal furnace is reduced to 1750APC within 60 minutes, the diameter of the single crystal silicon is 40mm (the first actual diameter). At this time, the actual diameter of the single crystal silicon does not reach 50mm. Therefore, in the second stage of the shoulder release process of the single crystal silicon, the power of the single crystal furnace is controlled to be reduced to the second preset power value within the second preset time. According to the formula, the second preset time = the fourth preset time - (the first preset diameter - the first actual diameter) * 2 = 40 - (50-40) * 2 = 20 minutes. Therefore, in the second stage of the shoulder release process of the single crystal silicon, the power of the single crystal furnace is controlled to be reduced to 1700APC within 20 minutes.

[0043] In some embodiments of the present invention, the second preset time is greater than or equal to 10 minutes. Since the temperature in the single crystal furnace fluctuates greatly during the process of the power of the single crystal furnace decreasing to the second preset power value within less than 10 minutes, the growth process of the single crystal silicon is affected. Therefore, by setting the second preset time to be greater than or equal to 10 minutes, the growth process of the single crystal silicon is further guaranteed and the quality of the single crystal silicon is improved.

[0044] Furthermore, the shoulder release method for single crystal silicon also includes determining that the second preset time is less than 10 minutes, and controlling the power of the single crystal furnace to be reduced to the second preset power value within 10 minutes, thereby ensuring the growth of single crystal silicon through such a setting.

[0045] In some embodiments of the present invention, the calculation formula of the third preset time is: third preset time=(first preset time-first actual time)*2+fourth preset time.

[0046] It can be understood that in the process of preset shouldering process of single crystal silicon in an ideal state, the first stage of shouldering process of single crystal silicon: the power of single crystal furnace is reduced to the first preset power value within the first preset time, and the diameter of single crystal silicon reaches the first preset diameter; the second stage of shouldering process of single crystal silicon: the power of single crystal furnace is reduced to the second preset power value within the fourth preset time, and the diameter of single crystal silicon reaches the second preset diameter. Thus, by the first preset time, the fourth preset time and the first actual time when the single crystal silicon reaches the first preset diameter, and according to the formula: (first preset time-first actual time)*2+fourth preset time to obtain the third preset time, the power of the single crystal furnace is controlled to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within the third preset time from when the single crystal silicon reaches the first preset diameter.

[0047] For example, in a specific embodiment of the present invention, during the shoulder releasing process of the preset single crystal silicon in an ideal state, the initial power of the single crystal furnace is 1800APC (where 1KW=30APC), and the first stage of the shoulder releasing process of the single crystal silicon: the power of the single crystal furnace is reduced to 1750APC (first preset power value) within 60min (first preset time), and the diameter of the single crystal silicon reaches 50mm (first preset diameter); the second stage of the shoulder releasing process of the single crystal silicon: the power of the single crystal furnace is reduced to 1700APC (second preset power value) within 40min (fourth preset time), and the diameter of the single crystal silicon reaches 100mm (second preset diameter).

[0048] When the diameter of the single crystal silicon reaches 50mm, the shoulder releasing process of the single crystal furnace actually runs for 30min, which is less than 60min. At this time, the actual power of the single crystal furnace is 1770APC, and the shoulder releasing process of the single crystal silicon is in a low-temperature shoulder in the first stage. Therefore, in the second stage of the shoulder releasing process of the single crystal silicon, according to the formula, the third preset time = (first preset time - first actual time) * 2 + fourth preset time = (60-30) * 2 + 40 = 100min, therefore, when the single crystal silicon reaches 50mm, the power of the single crystal furnace is controlled to drop from 1770APC to 1700APC within 100min.

[0049] Or, when the diameter of the single crystal silicon reaches 50mm, the shoulder releasing process of the single crystal furnace actually runs for 60min, which is equal to 60min. At this time, the actual power of the single crystal furnace is 1750APC, and the shoulder releasing process of the single crystal silicon is in an ideal state in the first stage. Therefore, in the second stage of the shoulder releasing process of the single crystal silicon, according to the formula, the third preset time = (first preset time - first actual time) * 2 + fourth preset time = (60-60) * 2 + 40 = 40min, therefore, when the single crystal silicon reaches 50mm, the power of the single crystal furnace is controlled to drop from 1750APC to 1700APC within 40min.

[0050] In some embodiments of the present invention, the third preset time is less than or equal to 140 minutes. Since the power of the single crystal furnace is reduced to the second preset power value in more than 140 minutes, the single crystal furnace is in the second stage of the shoulder release process, resulting in the entire shoulder release process being too long, which is not conducive to the growth of single crystal silicon. Therefore, by setting the third preset time to be less than or equal to 140 minutes, the growth process of single crystal silicon is further guaranteed and the quality of single crystal silicon is improved.

[0051] Furthermore, the shoulder release method for single crystal silicon also includes determining that the third preset time is greater than 140 minutes, and controlling the power of the single crystal furnace to decrease to a second preset power value within 140 minutes, thereby ensuring the growth of single crystal silicon through such a setting.

[0052] In some embodiments of the present invention, Figure 1 As shown, after controlling the power of the single crystal furnace to decrease to a second preset power value within a second preset time, the shoulder release method further includes:

[0053] When the power of the single crystal furnace is reduced to the second preset power value, it is determined that the diameter of the single crystal silicon has not reached the second preset diameter. It can be understood that since the real-time diameter of the single crystal silicon obtained within the first preset time does not reach the first preset diameter, it means that the shoulder release this time is a high-temperature shoulder. Therefore, it is necessary to shorten the time for the power of the single crystal furnace to be reduced to the second preset power value. Therefore, when the power of the single crystal furnace is reduced to the second preset power value, the actual diameter of the single crystal silicon has not reached the second preset diameter. Therefore, it is necessary to wait for the actual diameter of the single crystal silicon to grow to the second preset value diameter before entering the next shoulder release stage to ensure that the actual diameter of the single crystal silicon grows as much as possible according to the preset diameter.

[0054] The single crystal furnace is controlled to keep running at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter, and the second preset diameter is greater than the first preset diameter. It can be understood that when the power of the single crystal furnace is reduced to the second preset power value, and in the process of the actual diameter of the single crystal silicon growing to the second preset diameter, the single crystal silicon is controlled to continue to grow in the state of the single crystal furnace being at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter and then enters the next shoulder release stage, thereby ensuring that the actual diameter of the single crystal silicon grows as close to the preset diameter as possible.

[0055] In some embodiments of the present invention, Figure 1 As shown, the power of the single crystal furnace is controlled to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time from when the single crystal silicon reaches the first preset diameter, wherein after the third preset time is greater than the second preset time, the shoulder release method further includes:

[0056] It is determined that the diameter of the silicon monocrystalline reaches the second preset diameter and the second actual time for the diameter of the silicon monocrystalline to reach the second preset diameter is less than the third preset time, and the second preset diameter is greater than the first preset diameter. It can be understood that when the first actual time for the silicon monocrystalline to reach the first preset diameter is less than the first preset time, it means that the shoulder is a low-temperature shoulder, and therefore, it is necessary to extend the time for the power of the single crystal furnace to be reduced to the second preset power value. Thus, when the actual diameter of the silicon monocrystalline reaches the second preset diameter, the second actual time for the single crystal furnace to actually operate is less than the third preset time, and therefore, the actual diameter of the silicon monocrystalline needs to continue to grow until the second actual time is equal to the third preset time.

[0057] The pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon until the third preset time is reached. Thus, after the actual diameter of the single crystal silicon reaches the second preset diameter, the pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon until the third preset time is reached. Specifically, when it is determined that the diameter of the single crystal silicon reaches the second preset diameter and the second actual time when the diameter of the single crystal silicon reaches the second preset diameter is less than the third preset time, the current length of the single crystal silicon is cleared and 0mm is used as the starting value of the length, and the pulling speed of the single crystal silicon corresponding to the length increase in the shoulder release parameters of the single crystal silicon shown in Table 1 is operated until the second actual time of the actual operation of the single crystal furnace is equal to the third preset time. For example, after the current length of the single crystal silicon is cleared, the pulling speed of the single crystal silicon is controlled to be 1.25mm / min during the process of the length of the single crystal silicon from 0mm-10mm, and the pulling speed of the single crystal silicon is controlled to be 1.30mm / min during the process of the length of the single crystal silicon from 10mm-20mm.

[0058] Table 1 Shoulder parameters of single crystal silicon Table 1 shows various data corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon obtained when the shoulder release process of single crystal silicon is in an ideal state according to a specific embodiment of the present invention.

[0059] In some embodiments of the present invention, Figure 1 As shown, the shoulder release method also includes:

[0060] The power of the single crystal furnace is adjusted according to the length of the single crystal silicon. It is understandable that after the step of controlling the single crystal furnace to maintain operation at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter, or after the step of controlling the pulling speed of the single crystal silicon according to the length of the single crystal silicon until the third preset time is reached, the shouldering process of the single crystal silicon enters the next stage, that is, adjusting the power of the single crystal furnace according to the length of the single crystal silicon.

[0061] Specifically, when the single crystal furnace is controlled to maintain operation at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter, or when the pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon until the third preset time is reached, the current length of the single crystal silicon is cleared and 0 mm is used as the starting value of the length, and the pulling speed of the single crystal silicon corresponding to the length increase in the shoulder release parameters of the single crystal silicon shown in Table 1 is operated so that the diameter of the single crystal silicon continues to grow. For example, after the current length of the single crystal silicon is cleared, the pulling speed of the single crystal silicon is controlled to be 1.25 mm / min during the process of the length of the single crystal silicon from 0 mm to 10 mm, and the pulling speed of the single crystal silicon is controlled to be 1.30 mm / min during the process of the length of the single crystal silicon from 10 mm to 20 mm.

[0062] In some embodiments of the present invention, Figure 1 As shown, the shoulder release method also includes:

[0063] It is determined that the diameter of the silicon single crystal reaches a third preset diameter, and the third preset diameter is greater than the second preset diameter. It can be understood that through the above steps, the power of the single crystal furnace is adjusted according to the length of the silicon single crystal, so that after the diameter of the silicon single crystal reaches the third preset diameter, the shoulder release process enters the final stage.

[0064] Taking the current power value of the single crystal furnace as the starting value, the power value of the single crystal furnace is uniformly reduced to the third preset power value according to the growth rate of the diameter of the single crystal silicon during the process of the diameter of the single crystal silicon increasing from the third preset diameter to the fourth preset diameter, and the fourth preset diameter is greater than the third preset diameter.

[0065] It is understandable that in the growth process of monocrystalline silicon, there are other processes after the shoulder release process. Therefore, at the end of the shoulder release process, the final diameter of the monocrystalline silicon and the power of the monocrystalline furnace are guaranteed to meet the requirements of the next process. Therefore, by taking the current power value of the monocrystalline furnace as the starting value, the fourth preset diameter as the final diameter of the monocrystalline silicon, and the third preset power value as the final power value of the monocrystalline furnace in the shoulder release process, the power value of the monocrystalline furnace is uniformly reduced to the third preset power value according to the growth rate of the diameter of the monocrystalline silicon during the process of the diameter of the monocrystalline silicon from the third preset diameter to the fourth preset diameter, so that the final diameter of the monocrystalline silicon and the power of the monocrystalline furnace at the end of the last stage of the shoulder release process meet the requirements of the next process.

[0066] For example, in a specific embodiment of the present invention, the final diameter of the single crystal silicon is 200 mm, and the final power value of the single crystal furnace in the shoulder release process is 1575 APC.

[0067] In the first stage of the shoulder releasing process of single crystal silicon, when the power of the single crystal furnace is reduced to 1750APC within 60 minutes, the diameter of the single crystal silicon is 40mm (first actual diameter). At this time, the actual diameter of the single crystal silicon does not reach 50mm. Therefore, in the second stage of the shoulder releasing process of single crystal silicon, the power of the single crystal furnace is controlled to be reduced to the second preset power value within the second preset time. According to the formula, the second preset time = the fourth preset time - (the first preset diameter - the first actual diameter) * 2 = 40 - (50-40) * 2 = 20min. Therefore, in the second stage of the shoulder releasing process of single crystal silicon, the power of the single crystal furnace is controlled to be reduced to 1700APC within 20 minutes. Since the diameter of the single crystal silicon does not reach 100mm when the power of the single crystal furnace is reduced to 1700APC, the single crystal furnace is kept running at 1700APC until the diameter of the single crystal silicon reaches 100mm and enters the third stage of the shoulder releasing process. In the third stage of the shoulder release process of the single crystal silicon, the power of the single crystal furnace is adjusted according to the length of the single crystal silicon until the diameter of the single crystal silicon reaches 140mm and then the fourth stage of the shoulder release process is entered. In the fourth stage of the shoulder release process of the single crystal silicon, the current power value of the single crystal furnace is 1700APC as the starting value, and the power value of the single crystal furnace is uniformly reduced to 1575APC according to the growth rate of the diameter of the single crystal silicon during the process of the diameter of the single crystal silicon increasing from 140mm to 200mm.

[0068] In the first stage of the shoulder releasing process of single crystal silicon, and when the diameter of single crystal silicon reaches 50mm, the shoulder releasing process of the single crystal furnace actually runs for 30min, which is less than 60min. At this time, the actual power of the single crystal furnace is 1770APC, and the shoulder releasing process of single crystal silicon is in a low-temperature shoulder in the first stage. Therefore, in the second stage of the shoulder releasing process of single crystal silicon, according to the formula, the third preset time = (first preset time - first actual time) * 2 + fourth preset time = (60-30) * 2 + 40 = 100min, therefore, when the single crystal silicon reaches 50mm, the power of the single crystal furnace is controlled to decrease from 1770APC to 1700APC within 100min. Since the actual running time of the single crystal furnace is less than 100min when the actual diameter of the single crystal silicon reaches 100mm, the pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon until it reaches 100min and enters the third stage of the shoulder releasing process. At this time, the diameter of the single crystal silicon is 120mm. In the third stage of the shoulder release process of the single crystal silicon, the power of the single crystal furnace is adjusted again according to the length of the single crystal silicon until the diameter of the single crystal silicon reaches 140mm and then the fourth stage of the shoulder release process is entered. In the fourth stage of the shoulder release process of the single crystal silicon, the current power value of the single crystal furnace is 1700APC as the starting value, and the power value of the single crystal furnace is uniformly reduced to 1575APC according to the growth rate of the diameter of the single crystal silicon during the process of the diameter of the single crystal silicon increasing from 140mm to 200mm.

[0069] In the first stage of the shoulder releasing process of single crystal silicon, and when the diameter of the single crystal silicon reaches 50mm, the shoulder releasing process of the single crystal furnace actually runs for 60min, which is equal to 60min. At this time, the actual power of the single crystal furnace is 1750APC, and the shoulder releasing process of the single crystal silicon is in an ideal state in the first stage. Therefore, in the second stage of the shoulder releasing process of single crystal silicon, according to the formula, the third preset time = (first preset time - first actual time) * 2 + fourth preset time = (60-60) * 2 + 40 = 40min, therefore, when the single crystal silicon reaches 50mm, the power of the single crystal furnace is controlled to be reduced from 1750APC to 1700APC within 40min. Since the diameter of the single crystal silicon reaches 100mm when the power of the single crystal furnace is reduced to 1700APC, it directly enters the third stage of the shoulder releasing process. In the third stage of the shoulder release process of the single crystal silicon, the power of the single crystal furnace is adjusted again according to the length of the single crystal silicon until the diameter of the single crystal silicon reaches 140mm and then the fourth stage of the shoulder release process is entered. In the fourth stage of the shoulder release process of the single crystal silicon, the current power value of the single crystal furnace is 1700APC as the starting value, and the power value of the single crystal furnace is uniformly reduced to 1575APC according to the growth rate of the diameter of the single crystal silicon during the process of the diameter of the single crystal silicon increasing from 140mm to 200mm.

[0070] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, the shoulder release method also includes:

[0071] The actual diameter of the single crystal silicon is obtained, and it is determined whether the actual diameter reaches the fork diameter or whether the shoulder release operation time of the single crystal silicon reaches the fork setting time. It is understandable that when the actual diameter of the single crystal silicon does not reach the fork diameter or the shoulder release operation time of the single crystal silicon reaches the fork setting time, the single crystal silicon does not need to be forked; when the actual diameter of the single crystal silicon reaches the fork diameter or the shoulder release operation time of the single crystal silicon reaches the fork setting time, the single crystal silicon needs to be forked, and the shoulder release time of different single crystal silicon or the length of the single crystal silicon has different requirements for the width of the fork, so that the fork width of the single crystal silicon grows as much as possible according to the target fork width, so as to better control the shoulder shape of the single crystal silicon, and then effectively avoid the low shoulder release survival rate caused by the non-uniform shoulder shape during the shoulder release process, thereby ensuring the survival rate and quality of the single crystal silicon.

[0072] If not, and the single crystal silicon is forked, the pulling speed is increased based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. It can be understood that since the pulling speed of the single crystal silicon affects the width of the fork of the single crystal silicon, and the faster the pulling speed of the single crystal silicon, the smaller the width of the fork of the single crystal silicon, therefore, when the actual diameter of the single crystal silicon does not reach the fork diameter or the shoulder release operation time of the single crystal silicon does not reach the fork setting time, the single crystal silicon is forked, and it is necessary to increase the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, so as to avoid the single crystal silicon from forking, so that the fork width of the single crystal silicon can grow as much as possible according to the target fork width, so as to better control the timing of shoulder release and fork release, and improve the success rate of shoulder release of the single crystal silicon.

[0073] Furthermore, the calculation formula for improving the pulling speed is based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon: (actual fork width of the single crystal silicon - target fork width of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon) * stage speed adjustment ratio of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon * target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon.

[0074] If so, the pulling speed of the single crystal silicon is controlled according to the actual split width of the single crystal silicon. Thus, when the actual diameter of the single crystal silicon reaches the split diameter or the shouldering operation time of the single crystal silicon reaches the split setting time, the pulling speed of the single crystal silicon is controlled after comparing the actual split width of the single crystal silicon obtained in real time with the target split width, so that the split width of the single crystal silicon grows as close to the target split width as possible. It should be noted that controlling the pulling speed of the single crystal silicon according to the actual split width of the single crystal silicon is specifically described in the subsequent embodiments.

[0075] Furthermore, an image is captured by a camera fixed on the single crystal furnace and the width of the fork is calculated by an algorithm, thereby obtaining the actual fork width of the single crystal silicon in real time.

[0076] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, controlling the pulling speed of the single crystal silicon according to the actual fork width of the single crystal silicon includes:

[0077] If the actual fork width is smaller than the target fork width, the pulling speed is reduced based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Since the pulling speed of the single crystal silicon affects the fork width of the single crystal silicon, and the slower the pulling speed of the single crystal silicon, the larger the fork width of the single crystal silicon, therefore, when the actual fork width of the single crystal silicon obtained in real time is smaller than the target fork width, the pulling speed is reduced based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, thereby increasing the fork width of the single crystal silicon, so that the fork width of the single crystal silicon grows as close to the target fork width as possible.

[0078] The shoulder releasing process of single crystal silicon includes the above-mentioned first stage, second stage, third stage and fourth stage. After the actual diameter of the single crystal silicon reaches the fork opening diameter or it is judged that the shoulder releasing operation time of the single crystal silicon reaches the fork opening setting time, the shoulder releasing time of the single crystal silicon corresponding to different stages or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon are specifically explained according to the shoulder releasing parameters of the single crystal silicon shown in Table 1.

[0079] The first stage of the shoulder release process of single crystal silicon is to control the power of the single crystal furnace to be reduced to the first preset power value within the first preset time. Therefore, the first stage is a power reduction corresponding to time. Therefore, in the first stage, the target pulling speed value of the single crystal furnace is determined according to the shoulder release time of the single crystal silicon in the shoulder release parameters of the single crystal silicon shown in Table 1. For example, in a specific embodiment of the present invention, during the shoulder release time of the single crystal silicon running from 0min to 10min, the target pulling speed value of the single crystal silicon is 1.30mm / min, and during the shoulder release time of the single crystal silicon running from 10min to 20min, the target pulling speed value of the single crystal silicon is 1.25mm / min.

[0080] The second stage of the shoulder release process of single crystal silicon executes different steps according to the judgment in the first stage that the shoulder release is in a high temperature shoulder, a low temperature shoulder or an ideal state.

[0081] When the shoulder release is at a high temperature shoulder, the second stage of the shoulder release process of the single crystal silicon is to control the power of the single crystal furnace to be reduced to the second preset power value within the second preset time, and control the single crystal furnace to keep running at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter. Therefore, the second stage of the high temperature shoulder is a power reduction corresponding to time. Therefore, the target pulling speed value of the single crystal furnace in the second stage of the high temperature shoulder is determined according to the shoulder release time of the single crystal silicon in the shoulder release parameters of the single crystal silicon shown in Table 1. For example, in a specific embodiment of the present invention, since the first stage of the high temperature shoulder lasts for 60 minutes and enters the second stage after 60 minutes, the target pulling speed value of the single crystal silicon is 1.05 mm / min during the shoulder release time of the single crystal silicon running for 60 minutes to 75 minutes, and the target pulling speed value of the single crystal silicon is 1.15 mm / min during the shoulder release time of the single crystal silicon running for 75 minutes to 100 minutes.

[0082] When the shoulder release is in an ideal state, the power of the single crystal furnace is controlled to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within the third preset time from the time when the single crystal silicon reaches the first preset diameter. Since the shoulder release time runs until the third preset time, the actual power value of the single crystal furnace is reduced to the second preset power value, and the diameter of the single crystal silicon grows to the second preset diameter. Therefore, the second stage of the ideal state is a power reduction corresponding to time. Therefore, the target pulling speed value of the single crystal furnace in the second stage of the ideal state is determined according to the shoulder release time of the single crystal silicon in the shoulder release parameters of the single crystal silicon shown in Table 1. For example, in a specific embodiment of the present invention, since the first stage of the high-temperature shoulder lasts for 60 minutes, the second stage is entered after 60 minutes. During the process of the shoulder release time of the single crystal silicon running for 60 minutes to 75 minutes, the target pulling speed value of the single crystal silicon is 1.05 mm / min, and during the process of the shoulder release time of the single crystal silicon running for 75 minutes to 100 minutes, the target pulling speed value of the single crystal silicon is 1.15 mm / min.

[0083] When the shoulder release is in the low-temperature shoulder, the second stage of the shoulder release process of the single crystal silicon is to control the power of the single crystal furnace to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within the third preset time from the time when the single crystal silicon reaches the first preset diameter. Before the single crystal silicon is reduced to the second preset power value, the diameter of the single crystal silicon first reaches the second preset diameter. Therefore, after determining that the diameter of the single crystal silicon reaches the second preset diameter and the second actual time when the diameter of the single crystal silicon reaches the second preset diameter is less than the third preset time, the pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon until the third preset time is reached.

[0084] Therefore, the second stage of the low temperature shoulder is a power reduction corresponding to time before the diameter of the single crystal silicon reaches the second preset diameter. Therefore, the target pulling speed value of the single crystal furnace in the second stage of the low temperature shoulder is determined according to the shoulder release time of the single crystal silicon in the shoulder release parameters of the single crystal silicon shown in Table 1. After the diameter of the single crystal silicon reaches the second preset diameter, the pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon between the second actual time when the diameter of the single crystal silicon reaches the second preset diameter and the third preset time. Therefore, the target pulling speed value of the single crystal furnace in the second stage of the high temperature shoulder is determined according to the length of the single crystal silicon in the shoulder release parameters of the single crystal silicon shown in Table 1.

[0085] For example, in a specific embodiment of the present invention, since the diameter of the single crystal silicon reaches 50mm when the low-temperature shoulder runs for 30min in the first stage, the second stage is entered after 30min. Before the diameter of the single crystal silicon reaches 100mm, the target pulling speed value of the single crystal furnace is determined according to the shoulder release time of the single crystal silicon in the shoulder release parameters of the single crystal silicon shown in Table 1. For example, during the shoulder release time of the single crystal silicon running for 30min-40min, the target pulling speed value of the single crystal silicon is 1.20mm / min, and during the shoulder release time of the single crystal silicon running for 40min-50min, the target pulling speed value of the single crystal silicon is 1.15mm / min. After the diameter of the single crystal silicon reaches 50mm, the actual shoulder release time of the single crystal silicon is 60min, which is less than the third preset time of 100min. Therefore, after the actual shoulder release time of the single crystal silicon reaches 60min, the current length of the single crystal silicon is cleared and 0mm is used as the starting value of the length, and the pulling speed of the single crystal silicon corresponding to the length increase in the shoulder release parameters of the single crystal silicon shown in Table 1 is operated. For example, after the current length of the single crystal silicon is reset to zero, the target pulling speed value of the single crystal silicon is 1.25mm / min during the process of the length of the single crystal silicon changing from 0mm to 10mm, and the target pulling speed value of the single crystal silicon is 1.30mm / min during the process of the length of the single crystal silicon changing from 10mm to 20mm.

[0086] The third stage of the shoulder release process of monocrystalline silicon is to adjust the power of the single crystal furnace according to the length of the monocrystalline silicon. Therefore, the third stage is to reduce the power according to the length. Therefore, in the third stage, the current length of the monocrystalline silicon is reset to zero and 0mm is used as the starting value of the length. The pulling speed of the monocrystalline silicon corresponding to the length increase in the shoulder release parameters of the monocrystalline silicon shown in Table 1 is operated. For example, after the current length of the monocrystalline silicon is reset to zero, the target pulling speed value of the monocrystalline silicon is 1.25mm / min in the process of the length of the monocrystalline silicon from 0mm to 10mm, and the target pulling speed value of the monocrystalline silicon is 1.30mm / min in the process of the length of the monocrystalline silicon from 10mm to 20mm.

[0087] The fourth stage of the shoulder release process of single crystal silicon is based on the current power value of the single crystal furnace as the starting value. In the process of the diameter of the single crystal silicon changing from the third preset diameter to the fourth preset diameter, the power value of the single crystal furnace is uniformly reduced to the third preset power value according to the growth rate of the diameter of the single crystal silicon. The fourth stage is based on the power reduction corresponding to the length. Therefore, the fourth stage is to continue the length of the single crystal silicon in the third stage, and run according to the pulling speed of the single crystal silicon corresponding to the length increase in the shoulder release parameters of the single crystal silicon shown in Table 1. For example, at the end of the third stage, the length of the single crystal silicon is 50mm. In the fourth stage, the target pulling speed value of the single crystal silicon is 1.20mm / min during the process of the length of the single crystal silicon changing from 50mm to 65mm. The target pulling speed value of the single crystal silicon is 1.15mm / min during the process of the length of the single crystal silicon changing from 65mm to 80mm.

[0088] It should be noted that the target fork width is also the target fork width corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Since the above has discussed in detail the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon at different stages according to the shoulder release parameters of the single crystal silicon shown in Table 1, we will not elaborate on the target fork width of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon at different stages according to the shoulder release parameters of the single crystal silicon shown in Table 1.

[0089] If the actual split width is greater than or equal to the target split width, the pulling speed of the single crystal silicon is controlled according to the actual diameter change rate of the single crystal silicon. It is understandable that when the temperature in the single crystal furnace fluctuates, the fixed pulling speed of the single crystal furnace is prone to shoulder failure, and the pulling speed of the single crystal furnace controls the growth of the length, diameter and split width of the single crystal furnace. Therefore, after the actual split width is greater than or equal to the target split width, the pulling speed of the single crystal furnace is adjusted by real-time detection of the actual diameter change rate of the single crystal silicon, so as to avoid shoulder failure caused by unstable control temperature as much as possible, and further improve the survival rate of the single crystal silicon. It should be noted that controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon is specifically described in the subsequent embodiments. At the same time, by obtaining the diameter change rate of the single crystal silicon for a certain period of time in real time, the growth process of the diameter of the single crystal silicon can be better judged.

[0090] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon includes:

[0091] The pulling speed of the single crystal furnace is controlled to be reduced from the target pulling speed value to the first lower limit pulling speed value. It is understandable that when the actual fork width of the single crystal silicon detected in real time is less than the target fork width, the pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon is reduced to the first lower limit pulling speed value, thereby increasing the fork width of the single crystal silicon, so that the fork width of the single crystal silicon grows as close to the target fork width as possible.

[0092] The single crystal furnace is controlled to increase at the first pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Thus, after the single crystal furnace is reduced to the first lower limit pulling speed value, the single crystal furnace is controlled to increase at the first pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon to ensure the growth of the single crystal silicon.

[0093] Furthermore, the first pulling speed is 0.05 mm / min per second, thereby ensuring the growth of single crystal silicon and improving the survival rate.

[0094] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, the time for which the pulling speed of the single crystal furnace maintains the first lower limit pulling speed value is less than or equal to the first lower limit time. Therefore, by limiting the first lower limit time, it is prevented that the pulling speed of the single crystal furnace is at the first lower limit pulling speed value for too long to affect the survival rate of the single crystal silicon.

[0095] Furthermore, the shoulder release method of single crystal silicon also includes, after the pulling speed of the single crystal furnace maintains a first lower limit pulling speed value for a time equal to the first lower limit time, controlling the single crystal furnace to increase at the first pulling speed to the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon, and again controlling the pulling speed of the single crystal silicon according to the actual fork width of the single crystal silicon.

[0096] In some embodiments of the present invention, Figure 1 and Figure 2As shown, the calculation formula of the first lower limit pulling speed value is: (actual split width of single crystal silicon - target split width of single crystal furnace corresponding to shoulder release time of single crystal silicon or length of single crystal silicon) * stage speed adjustment ratio of single crystal furnace corresponding to shoulder release time of single crystal silicon or length of single crystal silicon * target pulling speed value of single crystal furnace corresponding to shoulder release time of single crystal silicon or length of single crystal silicon. It can be understood that the shoulder release process of single crystal silicon includes the above-mentioned first stage, second stage, third stage and fourth stage, and at different stages, according to the target split width corresponding to shoulder release time of single crystal silicon or length of single crystal silicon, stage speed adjustment ratio and target pulling speed value and actual split width of single crystal silicon, and the first lower limit pulling speed value is calculated according to the above formula, so that the actual split width of single crystal silicon detected in real time is less than the target split width, and the pulling speed of the single crystal furnace is controlled to be reduced to the first lower limit pulling speed value, thereby increasing the split width of single crystal silicon, so that the split width of single crystal silicon grows as much as possible according to the target split width.

[0097] It should be noted that the target fork width, stage speed adjustment ratio and target pulling speed value of the single crystal furnace are all the target fork width, stage speed adjustment ratio and target pulling speed value corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Since the above has discussed in detail the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon at different stages according to the shoulder release parameters of the single crystal silicon shown in Table 1, we will not elaborate on the target fork width and stage speed adjustment ratio of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon at different stages according to the shoulder release parameters of the single crystal silicon shown in Table 1.

[0098] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon includes:

[0099] If the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is greater than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed is increased on the basis of the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. It can be understood that since the pulling speed of the single crystal silicon affects the diameter of the single crystal silicon, and the slower the pulling speed of the single crystal silicon, the larger the length of the diameter of the single crystal silicon, when the actual diameter change rate of the detected single crystal silicon is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is greater than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed is increased on the basis of the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, so that the actual diameter of the single crystal silicon grows as much as possible according to the preset diameter, thereby ensuring the survival rate and quality of the single crystal silicon.

[0100] Furthermore, on the basis of the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon, the calculation formula for pulling speed is added: (actual diameter change rate of single crystal silicon - target diameter change rate of single crystal silicon corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon) * stage speed adjustment ratio of single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon * target pulling speed value of the single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon.

[0101] Furthermore, in the process of controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon, it is detected in real time whether the actual fork width of the single crystal silicon reaches the target fork width. If not, the pulling speed of the single crystal silicon is controlled according to the actual fork width of the single crystal silicon.

[0102] If the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed is reduced on the basis of the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Thus, by reducing the pulling speed on the basis of the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the actual diameter of the single crystal silicon grows as close to the preset diameter as possible, thereby ensuring the survival rate and quality of the single crystal silicon.

[0103] Furthermore, in the process of controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon, it is detected in real time whether the actual fork width of the single crystal silicon reaches the target fork width. If not, the pulling speed of the single crystal silicon is controlled according to the actual fork width of the single crystal silicon.

[0104] If the actual diameter change rate is equal to the target diameter change rate of the single crystal silicon corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, the actual pulling speed value of the single crystal furnace is maintained. It can be understood that at this time, the diameter growth of the single crystal silicon is produced according to the preset diameter, so the actual pulling speed value of the single crystal furnace is continued to be maintained to ensure the survival rate and quality of the single crystal silicon.

[0105] Furthermore, in the process of controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon, it is detected in real time whether the actual fork width of the single crystal silicon reaches the target fork width. If not, the pulling speed of the single crystal silicon is controlled according to the actual fork width of the single crystal silicon.

[0106] If the actual diameter change rate is less than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed is reduced based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Thus, by reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the actual diameter of the single crystal silicon grows as close to the preset diameter as possible, thereby ensuring the survival rate and quality of the single crystal silicon.

[0107] Furthermore, in the process of controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon, it is detected in real time whether the actual fork width of the single crystal silicon reaches the target fork width. If not, the pulling speed of the single crystal silicon is controlled according to the actual fork width of the single crystal silicon.

[0108] It should be noted that the target diameter change rate of single crystal silicon is the target diameter change rate of single crystal silicon corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon. Since the above has discussed in detail the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon at different stages according to the shoulder release parameters of single crystal silicon shown in Table 1, we will not elaborate on the target diameter change rate of single crystal silicon in the single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon at different stages according to the shoulder release parameters of single crystal silicon shown in Table 1.

[0109] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, the actual diameter change rate is less than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the pulling speed is reduced based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, including:

[0110] The single crystal furnace is controlled to reduce the pulling speed to the second lower limit pulling speed value at the second pulling speed. It can be understood that when the actual diameter change rate of the single crystal silicon is less than the target diameter change rate of the single crystal silicon corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, the second pulling speed is reduced to the second lower limit pulling speed value based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, thereby increasing the length of the diameter of the single crystal silicon, so that the diameter of the single crystal silicon grows as close to the target diameter as possible.

[0111] Furthermore, the second pulling speed is 0.01 mm / min per second, thereby ensuring the growth of single crystal silicon and improving the survival rate.

[0112] It is determined that the pulling speed of the single crystal furnace is reduced to a second lower limit pulling speed value.

[0113] The single crystal furnace is controlled to increase at the third pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the second pulling speed is less than the third pulling speed. Therefore, after the single crystal furnace is reduced to the second lower limit pulling speed value, the single crystal furnace is controlled to increase at the third pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, so as to ensure the growth of the single crystal silicon. At the same time, the decreasing speed of the pulling speed of the single crystal furnace is less than the increasing speed, so as to further ensure the growth of the single crystal silicon and improve the survival rate.

[0114] Furthermore, the third pulling speed is 0.05 mm / min per second, thereby ensuring the growth of single crystal silicon and improving the survival rate.

[0115] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, the time for the pulling speed of the single crystal furnace to maintain the second lower limit pulling speed value is less than or equal to the second lower limit time. Therefore, by limiting the second lower limit time, it is avoided that the pulling speed of the single crystal furnace is at the second lower limit pulling speed value for too long to affect the survival rate of the single crystal silicon.

[0116] In some embodiments of the present invention, Figure 1 and Figure 2 As shown, if the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon includes:

[0117] The pulling speed of the single crystal furnace is controlled to be reduced from the target pulling speed value to the third lower limit pulling speed value. It can be understood that when the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed value is reduced to the third lower limit pulling speed value based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, thereby increasing the length of the diameter of the single crystal silicon, so that the diameter of the single crystal silicon grows as close to the target diameter as possible.

[0118] The single crystal furnace is controlled to increase at the fourth pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon. Thus, after the single crystal furnace is reduced to the third lower limit pulling speed value, the single crystal furnace is controlled to increase at the fourth pulling speed to the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, so as to ensure the growth of the single crystal silicon. Further, the fourth pulling speed is 0.05 mm / min per 1 second, so as to ensure the growth of the single crystal silicon and improve the survival rate.

[0119] In some embodiments of the present invention, the calculation formula for the second lower limit pulling speed value or the third lower limit pulling speed value is: (actual diameter change rate of the single crystal silicon - target diameter change rate of the single crystal silicon corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon) * stage speed adjustment ratio of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon * target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon. It can be understood that the shoulder release process of single crystal silicon includes the above-mentioned first stage, second stage, third stage and fourth stage. In different stages, the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the stage speed adjustment ratio of the single crystal furnace and the target pulling speed value of the single crystal furnace are used, and the second lower limit pulling speed value or the third lower limit pulling speed value is calculated according to the above formula, so that when the actual diameter change rate is less than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed of the single crystal furnace is controlled to be reduced to the second lower limit pulling speed value, or, when the actual diameter change rate is greater than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed of the single crystal furnace is controlled to be reduced to the third lower limit pulling speed value, thereby increasing the length of the diameter of the single crystal silicon, so that the fork width of the single crystal silicon grows as much as possible according to the target diameter.

[0120] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0121] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for shouldering single crystal silicon, characterized in that: include: Controlling the power of the single crystal furnace to decrease to a first preset power value within a first preset time; Acquiring the diameter of the single crystal silicon in real time, and determining whether the diameter of the single crystal silicon reaches the first preset diameter within the first preset time; If the diameter of the silicon single crystal does not reach the first preset diameter, controlling the power of the single crystal furnace to decrease to a second preset power value within a second preset time; If the diameter of the silicon single crystal reaches the first preset diameter, obtaining a first actual time when the silicon single crystal reaches the first preset diameter; Determine that the first actual time is less than or equal to the first preset time, and control the power of the single crystal furnace to be reduced from the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time starting from when the single crystal silicon reaches the first preset diameter, wherein the third preset time is greater than the second preset time.

2. The method for shouldering single crystal silicon according to claim 1, characterized in that: Within the first preset time, if the diameter of the single crystal silicon does not reach the first preset diameter, and the diameter of the single crystal silicon after the first preset time is the first actual diameter, the calculation formula for the second preset time is: The second preset time=the fourth preset time-(the first preset diameter-the first actual diameter)*2.

3. The method for shouldering single crystal silicon according to claim 1, characterized in that: The second preset time is greater than or equal to 10 minutes.

4. The method for shouldering single crystal silicon according to claim 1, characterized in that: The calculation formula of the third preset time is: The third preset time=(the first preset time-the first actual time)*2+the fourth preset time.

5. The method for shouldering single crystal silicon according to claim 1, characterized in that: The third preset time is less than or equal to 140 minutes.

6. The method for placing shoulders on single crystal silicon according to claim 1, characterized in that: After controlling the power of the single crystal furnace to decrease to a second preset power value within a second preset time, the shoulder release method further includes: When the power of the single crystal furnace is reduced to the second preset power value, determining that the diameter of the single crystal silicon does not reach the second preset diameter; The single crystal furnace is controlled to keep running at the second preset power value until the diameter of the single crystal silicon reaches the second preset diameter, and the second preset diameter is greater than the first preset diameter.

7. The method for shouldering single crystal silicon according to claim 1, characterized in that: In controlling the power of the single crystal furnace to reduce the actual power value of the single crystal furnace when the single crystal silicon reaches the first preset diameter to the second preset power value within a third preset time from when the single crystal silicon reaches the first preset diameter, wherein after the third preset time is greater than the second preset time, the shoulder release method further includes: Determining that the diameter of the silicon single crystal reaches a second preset diameter and a second actual time when the diameter of the silicon single crystal reaches the second preset diameter is less than the third preset time, and the second preset diameter is greater than the first preset diameter; The pulling speed of the single crystal silicon is controlled according to the length of the single crystal silicon until a third preset time is reached.

8. The method for shouldering single crystal silicon according to claim 6 or 7, characterized in that: The shoulder release method further comprises: The power of the single crystal furnace is adjusted according to the length of the single crystal silicon.

9. The method for shouldering single crystal silicon according to claim 8, characterized in that: The shoulder release method further comprises: Determining that the diameter of the silicon single crystal reaches a third preset diameter, wherein the third preset diameter is greater than the second preset diameter; Taking the current power value of the single crystal furnace as the starting value, the power value of the single crystal furnace is uniformly reduced to the third preset power value according to the growth rate of the diameter of the single crystal silicon during the process in which the diameter of the single crystal silicon increases from the third preset diameter to the fourth preset diameter, and the fourth preset diameter is larger than the third preset diameter.

10. The method for shouldering single crystal silicon according to claim 1, characterized in that: The shoulder release method further comprises: Obtaining the actual diameter of the single crystal silicon, determining whether the actual diameter reaches the split diameter or determining whether the single crystal silicon shoulder release operation time reaches the split setting time; If so, controlling the pulling speed of the single crystal silicon according to the actual split width of the single crystal silicon; If not, and the single crystal silicon is forked, the pulling speed is increased based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon.

11. The method for shouldering single crystal silicon according to claim 10, characterized in that: The controlling the pulling speed of the single crystal silicon according to the actual split width of the single crystal silicon comprises: If the actual fork width is smaller than the target fork width, the pulling speed is reduced based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon; If the actual split width is greater than or equal to the target split width, the pulling speed of the single crystal silicon is controlled according to the actual diameter change rate of the single crystal silicon.

12. The method for shouldering single crystal silicon according to claim 11, characterized in that: The reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon comprises: Controlling the pulling speed of the single crystal furnace to decrease from the target pulling speed value to a first lower limit pulling speed value; The single crystal furnace is controlled to increase at a first pulling speed to a target pulling speed value of the single crystal furnace corresponding to a shoulder time of the single crystal silicon or a length of the single crystal silicon.

13. The method for shouldering single crystal silicon according to claim 12, characterized in that: The pulling speed of the single crystal furnace is maintained at the first lower limit pulling speed value for a time that is less than or equal to the first lower limit time.

14. The method for shouldering single crystal silicon according to claim 12, characterized in that: The calculation formula of the first lower limit pulling speed value is: (Actual fork width of single crystal silicon - target fork width of single crystal furnace corresponding to shoulder release time of single crystal silicon or length of single crystal silicon)*stage speed adjustment ratio of single crystal furnace corresponding to shoulder release time of single crystal silicon or length of single crystal silicon*target pulling speed value of single crystal furnace corresponding to shoulder release time of single crystal silicon or length of single crystal silicon.

15. The method for shouldering single crystal silicon according to claim 11, characterized in that: The controlling the pulling speed of the single crystal silicon according to the actual diameter change rate of the single crystal silicon comprises: If the actual diameter change rate is greater than the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is greater than the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon, the pulling speed is increased on the basis of the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon; If the actual diameter change rate is greater than the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon, the pulling speed is reduced based on the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon; If the actual diameter change rate is equal to the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, the actual pulling speed value of the single crystal furnace is maintained; If the actual diameter change rate is smaller than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, the pulling speed is reduced based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon.

16. The method for shouldering single crystal silicon according to claim 15, characterized in that: The actual diameter change rate is less than the target diameter change rate of the single crystal silicon corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon, and reducing the pulling speed based on the target pulling speed value of the single crystal furnace corresponding to the shoulder release time of the single crystal silicon or the length of the single crystal silicon includes: Controlling the single crystal furnace to reduce the second pulling speed to a second lower limit pulling speed value; Determine that the pulling speed of the single crystal furnace is reduced to the second lower limit pulling speed value; The single crystal furnace is controlled to increase the third pulling speed to a target pulling speed value of the single crystal furnace corresponding to the shoulder time of the single crystal silicon or the length of the single crystal silicon, and the second pulling speed is less than the third pulling speed.

17. The method for shouldering single crystal silicon according to claim 16, characterized in that: The pulling speed of the single crystal furnace is maintained at the second lower limit pulling speed value for a time that is less than or equal to the second lower limit time.

18. The method for shouldering single crystal silicon according to claim 16, characterized in that: If the actual diameter change rate is greater than the shoulder release time of the single crystal silicon or the target diameter change rate of the single crystal silicon corresponding to the length of the single crystal silicon, and the actual pulling speed value of the single crystal furnace is less than the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon, reducing the pulling speed based on the shoulder release time of the single crystal silicon or the target pulling speed value of the single crystal furnace corresponding to the length of the single crystal silicon includes: Controlling the pulling speed of the single crystal furnace to decrease from the target pulling speed value to a third lower limit pulling speed value; The single crystal furnace is controlled to increase at a fourth pulling speed to a target pulling speed value of the single crystal furnace corresponding to a shoulder time of the single crystal silicon or a length of the single crystal silicon.

19. The method for shouldering single crystal silicon according to claim 18, characterized in that: The calculation formula of the second lower limit pulling speed value or the third lower limit pulling speed value is: (Actual diameter change rate of single crystal silicon - target diameter change rate of single crystal silicon corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon) * Stage speed adjustment ratio of single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon * Target pulling speed value of single crystal furnace corresponding to the shoulder release time of single crystal silicon or the length of single crystal silicon.

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